A handy way to beat the queues that can so often hold things up at the airport is to check-in online before your flight. Many airlines let you check-in up to 15 days before your flight so you can arrange this in plenty of time. Checking-in the online way allows you to go straight to security via the bag drop-off, saving you valuable time. If you have special requirements or do not use the internet, then check-in is still available in the normal way at your airline company's check-in desk within the airport.
While airlines vary in strictness with regards to their check-in policies, Virgin seems toughest. They will not make exceptions for anyone, no matter how heartrending your excuse for showing up late. So if you miss your check-in with them, your feet are stuck firmly to the ground unfortunately.
If you are checking-in at the airport, make sure you get there in plenty of time as sometimes check-in desks handle several flights at the same time, making for huge queues. Try to get there as soon as the desk opens to avoid delays. If the queue you are in is particularly long and you think this may cause you to miss your flight, then tell a member of staff immediately. If you are using a shared check-in desk you will be moved up the queue ahead of passengers queuing for later flights.
It pays to keep your eyes and ears open when you're finally airside. Keep tabs on your flight's boarding progress by watching monitors carefully for any updates. No one wants to see 'gate closed' up there, so make sure you make a move to board long before the last call.
You will be met with different responses from different airlines if you turn up late for boarding. Some airlines are stricter than others, with BA and Virgin stating that if the aircraft doors have closed, there's no way you're getting on board. Virgin are particularly tough when it comes to boarding times, warning that passengers who arrive at their gate less than 20 minutes before takeoff risk being barred. Your reasons for turning up late to your gate will usually hold some sway with the dispatcher, so if you have valid cause they may be more forgiving.
When the plane has well and truly left without you, you are very unlikely to get any sort of refund, but a transfer may be possible. The quicker you get to your carrier's information desk the better. Many airlines now offer rescue packages to those who have missed flights. This is where your carrier will get you on to the next available flight for a fee. You're likely to have more of a chance of transferring with charter carriers and low-cost airlines, who are a lot more flexible than the scheduled airlines.